JPS60902A - Method and device for molding powdered shape - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for molding a powder compact suitable for use in molding carbon or the like.

In the molding method using isostatic press, CI molding is performed at room temperature.
P (Cold l5ostatic Press) and
HIP molding under high temperature
c Press) is known. The present invention relates to the above CIP
It's about.

It is called a rubber press because it usually uses a rubber mold.
The method is divided into a wet method and a dry method depending on whether the rubber mold is submerged in water or not. In the wet method, the rubber mold is made of a thin rubber bag, and after the molding powder is packed into the bag, the two bags are tightly tied with rubber string, and then tied in several places to seal.

However, molding powder contains a large amount of air.

During molding, the molding powder and air are compressed, and the molding powder becomes a compact with a reduced volume. Then, as the pressure decreases, the rubber mold returns to almost its original volume.

The area around the molded body is filled with air extracted from the molded body.

By the way, when the particle size of the molding powder is extremely fine (average 10
μm or less), or when the molded product becomes large (1
50 rrag φ This is thought to be because the molding powder contains a lot of air in the wall, and the air is difficult to extract when the pressure is lowered. Therefore, a method is used to pump the thin rubber bag with a vacuum pump immediately before sealing it to expel the air inside the rubber bag, but this method still has the following problems.

That is, when degassing is performed using a vacuum pump, the inner surface of the rubber bag sticks together, making it impossible to suction sufficiently. If the degassing operation is continued in this state, the molding powder will be sucked in.

It is difficult to evacuate to a vacuum state.

Another disadvantage is that it is very troublesome and takes a long time to seal the opening of the rubber bag with a rubber cord while continuing to deaerate the bag. If this method is insufficient, water may enter the molded product and cause it to crack during pressurization, which requires a skilled handshake.

It is an object of the present invention to provide a method and apparatus for molding a powder compact that eliminates these drawbacks.

In the present invention, a stretchable bag is inserted into a bottomed cylinder with a large number of small holes, the upper part of the bag is locked to the upper part of the cylinder, and the bag is filled with molding powder. The body is placed in a vacuum chamber and degassed under reduced pressure.9Then, the cylinder is sealed with a lid through a bag, the pressure is returned to normal, and the cylinder is directly taken out from the chamber and pressurized using hydrostatic pressure to produce a powder compact. A molding method and an expandable bag for filling molding powder, a cylinder with a bottom that houses the bag and has a large number of small holes, and a lid that seals the cylinder through the bag. The present invention relates to a molding apparatus for powder compacts, which is equipped with a vacuum chamber and a cold isostatic pressurizing device, which accommodates a cylinder containing two bags of compacted powder and a lid, and has a mechanism for sealing the joints with the lid after depressurization.

The elastic bag is made of natural rubber, nitrile, and Buna N.
Rubber, silicone rubber, neoprene rubber, styrene rubber,
There is no restriction as long as it has good elongation and sealability, such as urethane rubber. What is the thickness of the rubber mold?

From something as thin as latex (0.2WrIn) to 3
up to about mm, preferably 0.3 to 1, 5
It is mm. If it is thinner than 0゜3m+n, the product will be cut off during work (
, l, If it is thicker than 5WM, it will be less flexible and difficult to handle.

The bottomed cylindrical body that houses the molded powder bag is made of a circular rigid body (hard vinyl chloride, steel, etc.) with numerous small holes through which pressurized water enters and exits during molding, and a removable seal on the top. For sealing, a bag is interposed between the cylindrical body and the lid, and the lid is preferably made of flexible material such as rubber. It is preferable to provide the same taper as the taper portion 3a on the side surface of the lid, as shown in FIG. The taper is 20 in the vertical direction of the cylinder.
A range of 80 degrees is preferred. To lock the bag to the upper part of the cylinder, it is easy and reliable to make the bag longer than the cylinder and fold it back from the upper end of the cylinder.

The vacuum chamber is made of material that can withstand a vacuum level of 10 Torr or less.

It is preferable to have a certain thickness, and the material is preferably steel.

In the vacuum chamber, the molded powder is fully decompressed and degassed, and then the lid is sealed on the cylinder. This operation is controlled remotely from outside the tank.
I'll do it for magic, etc.

The size of the vacuum chamber is designed in consideration of the above operations. It is preferable that a portion of the vacuum chamber be made of a transparent acrylic plate or the like so that the inside can be observed during operation.

The degree of vacuum during depressurization and deaeration is preferably 10 Torr or less, which can be achieved with an oil rotary pump, and heating may be performed below the heat resistant temperature of the bag, if necessary.

Since the volume of the molding powder decreases due to reduced pressure, in order to replenish the bag with molding powder in the vacuum tank, a container such as a hopper containing the molding powder is placed in the vacuum tank in advance, and A device may be added to the vacuum chamber for replenishing the bag with molding powder after the pressure is reduced at the same time as the container containing the molding powder. [fa] A door is provided in the vacuum chamber in order to take the body in and out of the vacuum chamber, but it goes without saying that an O-ring or rubber gasket should be used as appropriate to prevent air from entering through the door. The method of reducing the pressure, the cold isostatic pressurizing device, and the pressurizing method are based on known devices and methods.

Examples will be described below.

As shown in Figures 1 and 2, a bag made of natural rubber 1k
It is inserted into a basket 3 made of SUS 304, which is a bottomed cylinder of 250 mmφ
The tapered portion 3a of 5 degrees was folded back to allow filling of molding powder. A molded powder having an average particle diameter of 8 μn1 obtained by kneading and pulverizing pitch coke powder with a binder tar pitch is placed inside the bag 1 up to just below the tapered portion 3a. The basket 3 has a handle 5 rotatably attached to support shafts 4 and 4'.
, 5', and by lifting these upwards, the lid 6 made of dinitrile rubber is brought into close contact with the basket 3 through the bag body. The outer circumference of the lower surface of the lid 6 has a radius of 1 mm to facilitate close contact with the tapered part 3a of the basket 3.
It's obvious. Further, the basket 3 is provided with a large number of holes 7 having a diameter of 8 holes.

The basket 3 containing the molding powder 2 shown in FIG. 1 is placed uncovered in a vacuum chamber 8 as shown in FIG. 3. The lid 6 is suspended from the top of the basket 3 via an e wheel 18 by a nylon thread 9 wrapped around the shaft of a motor 11.
When the handles 5 and 5' are opened downward, the motor 12.13
It is connected by a nylon thread 10.10' wrapped around the shaft of. In this state, the vacuum chamber 8 is degassed to 8 Torr using an oil rotary vacuum pump (not shown), and then a switch (not shown) installed on the outside of the vacuum chamber is turned on to rotate the motor 11, as shown in FIG. Gently lower the lid 6 and place it on top of the basket 3. Next, motors 12 and 1
3 to wind up the nylon threads 10 and 10', and lift the handles 5 and 5' to fix the lid 6 to the basket 3. Open the vacuum pump purple stopper exhaust valve 14 and leak valve 15 to let air into the vacuum chamber and return it to normal pressure. , 10 and 1
0' is cut and the basket 3 is pulled out from the vacuum chamber. The lid 6 of the nooksket 3 was further securely fixed with a rubber string, and was molded by applying a hydrostatic pressure of 1 ton/an2 using a rubber press to obtain a carbon molded body having a size of 200111111φX 250111M.

This molded body and the fired product fired at 1iooo° C. were also free of oxidation.

According to the present invention, the air in the molding powder can be sufficiently removed without losing the molding powder during depressurization, thereby preventing cracking and cracking caused by the contained air, and making it possible to perform cumbersome and skilled work such as tying up the bags. does not require.

[Brief explanation of drawings]

Figure 1 is a sectional view showing how the basket is filled with molding powder, Figure 2 is a perspective view showing the lid fixed to the basket, and Figure 3 is a front sectional view of the basket and lid set in a vacuum chamber. , FIG. 4 is a side cross-sectional view showing a state in which the basket is covered with a lid inside the vacuum chamber. Explanation of symbols 1...Bag body 2...Molding powder 3...Basket 3a...Taber part 4.4'
...Support shaft 5,5'...Handle 6...Lid 7...
Hole 8...Vacuum chamber 9,9'...Nylon thread 10.10
'Nylon thread 11...Motor 12...Motor 13...Motor 14...Exhaust valve 15...
・Leak valve 16...Door 17...0 ring 18...Pulley

Claims (1)

[Claims] 1. A stretchable bag is inserted into a bottomed cylindrical body provided with a large number of small holes, and the upper part of the bag is locked to the upper part of the cylindrical body. After filling the bag with molding powder, the cylinder is placed in a vacuum chamber and degassed under reduced pressure.Then, the cylinder is sealed with a lid through the bag, and the pressure is returned to normal, and the cylinder is placed in a vacuum chamber. A method for molding a powder compact, characterized by taking it out from a powder body and pressurizing it by hydrostatic pressure. 2. A telescopic bag for filling molding powder, a cylinder with a bottom that houses the bag and has many small holes, a lid that seals the cylinder through the bag, and molding powder. A molding apparatus for powder compacts, which is equipped with a vacuum chamber having a mechanism for storing five bags of human bm bodies and a lid, and sealing the cylindrical body with the lid after depressurization, a cold isostatic pressurizing device, and a metal.